GaN transistors on Si for switching and high-frequency applications

Abstract

In this paper, recent advances of GaN transistors on Si for switching and high-frequency applications are reviewed. Novel epitaxial structures including superlattice interlayers grown by metal organic chemical vapor deposition (MOCVD) relieve the strain and eliminate the cracks in the GaN over large-diameter Si substrates up to 8 in. As a new device structure for high-power switching application, Gate Injection Transistors (GITs) with a p-AlGaN gate over an AlGaN/GaN heterostructure successfully achieve normally-off operations maintaining high drain currents and low onstate resistances. Note that the GITs on Si are free from current collapse up to 600 V, by which the drain current would be markedly reduced after the application of high drain voltages. Highly efficient operations of an inverter and DC-DC converters are presented as promising applications of GITs for power switching. The high efficiencies in an inverter, a resonant LLC converter, and a point-of-load (POL) converter demonstrate the superior potential of the GaN transistors on Si. As for high-frequency transistors, AlGaN/GaN heterojuction field-effect transistors (HFETs) on Si designed specifically for microwave and millimeter-wave frequencies demonstrate a sufficiently high output power at these frequencies. Output powers of 203 W at 2.5 GHz and 10.7 W at 26.5 GHz are achieved by the fabricated GaN transistors. These devices for switching and highfrequency applications are very promising as future energy-efficient electronics because of their inherent low fabrication cost and superior device performance.

On the origin of interface states at oxide/III-nitride heterojunction interfaces

“…[1][2][3][4][5][6][7][8] It was also well established that GaN-HEMTs with an insulated gate (IG) exhibit supremacy over Schottky-gate-based ones because of the lower gate leakage current, higher breakdown voltage, better thermal stability of the gate, and mitigation of current collapse. [8][9][10][11][12] The Al 2 O 3 and SiO 2 IG structures are particularly attractive for the application to GaN-HEMTs because of their favorable properties, i.e., the large conduction band (CB) offset at the insulator/semiconductor interfaces.…”

Characterization of capture cross sections of interface states in dielectric/III-nitride heterojunction structures

“…[1][2][3][4][5][6] It was demonstrated by many groups that GaN-HEMTs with an insulated gate (IG) structure, apart from being necessary for achieving normally off operation, exhibit important advantages over Schottkygate-based GaN-HEMTs such as lower gate leakage current, higher breakdown voltage, better thermal stability of the gate and less current collapse. [6][7][8][9][10] In order to obtain a good IG structure, suitable insulating materials such as Al 2 O 3 , SiO 2 , and SiN ensuring a large band offset and high permittivity are widely applied.…”

TMAH-based wet surface pre-treatment for reduction of leakage current in AlGaN/GaN MIS-HEMTs

“…AlGaN/GaN-based metal-insulator-semiconductor highelectron mobility transistors (MIS-HEMTs) have been studied for high frequency and high power applications, owing to outstanding material properties of III-nitrides such as a high electron mobility, a high electron saturation velocity, and a high breakdown electric field [1][2][3][4][5].…”